农业温室供热系统的研究和设计

1　引言温室内生产的蔬菜和花卉等作物 ,产量高 ,质量好 ,无污染。因此 ,它是现代化农业的重要标志。几年前 ,上海、北京等地已引进了荷兰、以色列、美国、法国等国外的温室 ,经过一段时间的运行 ,总体上还是比较成功的 ,积累了很多经验。然而 ,引进的温室存在如下的问题 :(1)温室的造价较贵 ,使得温室蔬菜作为商品的成本过高而无法进入普通百姓的家庭。(2 )温室的构造和配套的技术设备没有全面考虑我国的气象特点 ,而是基本照搬了国外技术 ,导致温室的年利用率降低。上海孙桥现代农业开发区与同济大学联手 ,在吸收和消化国外温室产品的基础…     

农业温室通风系统的设计与研究

中档连栋薄膜温室是一个大面积的农业温室;类似于多跨度的工业厂房,与单栋温室相比,其通风方式有其特殊性。本文从节约能源的角度,论述了利用热压、风压等原理、采用天窗、侧窗等方式,以得到较为满意的自然通风换气效果,同时提出了一些计算的方法。     

供热技术新领域-温室供热

针对严寒地区冬季温室农作物几乎不能生长的情况本文提出温室供热的必然性,可能性,必要性和重要性。在严密论证基础上,得出温室供热技术具有广阔的发展前景,将有助于我国农业现代化的实现。     

地热温室供热节能技术的研究

冬季加热是保证温室正常运行的首要条件．文中结合示范工程温室的运行与实地测量，从地热资源、温室结构、采暖管道布置、太阳能的利用及蓄热技术等方面分析了温室供热的节能措施，可为类似地热温室供暖系统节能设计提供一定的参考。     

单斜面温室的供热设计

单斜面温室是我国北方农村一种高效益、低成本、具有显著经济效益的生产设施。文章研究了单斜面温室在冬季或早春季节里的供暖问题,通过理论计算,给出了一种确定所需换热器数量的方法。     

供热系统的管理和新技术应用

供热系统一般是指锅炉房、热网管道、凝结水回收、管道保温、阀门、疏水阀和有关仪表。从广义上讲还应包括用热工艺上的合理用热,从目的上讲应包括安全、环保和节能。为了达到这些目的,必须要搞好供热系统的管理工作和不断采用新技术。目前上海的供热系统现状:上海供热系统能耗约占上海总能耗的20％左右,但供热系统热损失大,锅炉的平均运行效率布65％左右,热网管道损失在5～10％,疏水器的漏汽率大于10％,凝结水回收率极低。估计热网总损失在50％左右,而国外工业发达国家锅炉效率可达90％,热网管道损失在5％以内,疏水器漏汽率在3％以内,凝结水回收率可达60—80％,因此热网总损失可以降低到25％以下。二者相比,相差一倍以上,这说明我们上海供热系统的节能潜力很大,节能工作大有可为。 现在分别将目前上海这方面的情况简述如下:     

热水供暖供热系统的节能设计

热水供暖供热系统大流量、小温差运行必将带来高能耗。用于控制循环水泵动力消耗的指标—耗电输热比，应与热源和热用户型式、供回水温差和水泵效率等有关。以热水供暖供热系统水力计算结果为基础，根据并联环路节点压力平衡的水力学规律，利用热平衡的基本方程，导出的用于克服水力失调引起的热力失调的热用户换热设备面积修正系数的计算公式，可以用于节能型系统的设计。     

从节能角度谈居住建筑供热系统的设计

从热源、设备配置、热用户等方面,讨论寒冷区居住建筑供暖系统设计中,在节约能源方面所应考虑的问题。     

Energy consumption in greenhouses and selection of an optimized heating system with minimum energy consumption

In this paper, heat loss is precisely computed by a proposed code considering different climates. Estimating the costs of different central heating system, unit heaters were selected as the most feasible system. Finally, considering the heating capacity and unit heater's dimensions a computational fluid dynamics model was developed to find the optimized configuration of unit heaters in a typical greenhouse. Using this model, the required thermal load for a greenhouse based on the daily temperature of Arak city in 2017 was computed with a smart control system. It was found that savings in energy consumption were approximately 5447 m³ of natural gas each year.     

Modeling heat transfer and air circulation by convection in bottom-heated agricultural greenhouses

In agricultural greenhouses, effective heating systems are essential for maintaining proper temperature control and air circulation during the winter. This study delves into the analysis of heat exchange through natural convection within heated greenhouses, with a particular emphasis on the impact of bottom heating. Two distinct types: mono-chapel and bi-chapel, each featuring triangular or spherical roofs are examined. To capture the variable roof shapes, we employ a change-of-variable method, and the numerical solutions are obtained using the finite volume method. The results show that heat transfer is enhanced by increasing the Rayleigh number. This improvement differs according to the shape of the roof. Heat transfer decreases by about 5% for the spherical mono-chapel case compared to the triangular case for Ra = 10³. For Ra = 10⁵, the monospherical case favors heat transfer, with an increase of 0.35% compared to the triangular case. In the case of bi-chapel roof, heat transfer is greater with a triangular roof for Ra = 10³, showing an increase of 6.4% compared to the spherical case. This study not only sheds light on the fundamental aspects of heat transfer in greenhouses but also provides valuable insights for optimizing greenhouse design based on specific roof configurations and heating conditions.     

供暖系统规划设计中的几点节能分析

本文利用分析的原理,从节能的角度,对供暖系统在供暖方式、介质参数、供暖设备及管网调节方式等一系列问题进行了简要分析与比较,并提出了一些供暖系统的节能途径和措施。     

Meeting the electricity demand for the heating of greenhouses with hydrogen: Solar photovoltaic-hydrogen-heat pump system application in Turkey

Providing the heating system with coal in greenhouses causes harmful results in terms of carbon emissions. In this study, analyzes were performed to meet the electrical energy required for the heating system with a heat pump from a solar photovoltaic-hydrogen system. For floor area 25000 m² where greenhouses the required energy is obtained directly from hydrogen without using a heat pump 3000 m² solar panel area required. The use of a heat pump reduces energy needs but it is also not feasible for large greenhouses. For convenience, a solar photovoltaic-hydrogen-heat pump system analysis was also made for 1000 m² floor area greenhouses and it is found that the 24 m² solar panel area is adequate in terms of meeting energy demand. Using a solar-hydrogen-heat pump system reduces carbon emissions by 86.5 tons per 1000 m² floor area greenhouse. Considering the hydrogen storage system becomes unfeasible. We normalized the greenhouse floor area to 1 m² and proposed reference values for hydrogen to be produced in 1 h, storage, and PV area. In addition, an analysis was made for the use of hydrogen energy for greenhouses that do not require a heating system and only work with a water pump.     

Experimental study of the burning-cave hot water soil heating system in solar greenhouse

In the northern China areas, the traditional heating methods are widely used in solar greenhouse, for example: electric heating, hot air heating, hot water heating, burning-cave heating etc. If copying the assuring building indoor environment of constant heating ways into solar greenhouse, it will further increase building energy consumption, thus improving the efficiency of energy utilization, establishing appropriate growing environment, and realizing the agricultural waste recycling are important ways of consistent with the Chinese conditions, construction of sustainable development, improving the efficiency of the greenhouse production. To solve the problem of traditional heating method for high heating energy consumption, the inharmonious between greenhouse air temperature and soil temperature, uneven soil temperature, the research build the burning cave hot water soil heating system of solar greenhouse experimental platform in accordance with principle of energy cascade utilization. This experiment platform will transfer burning cave internal heat into soil heating system. The soil is evenly heated by system. Through testing the actual operation effect of the burning cave hot water soil heating system of new solar greenhouse, electric heating system, no taking any heating measures system, burning cave hot water soil heating system of solar greenhouse can improve the soil average temperature 5 ∼ 6 °C. This research provides experimental basis for practical applications and promotion.     

空气源-地板辐射采暖系统的应用研究

对地板辐射采暖系统在南方采用空气源热泵作为热源的优势进行了分析;并对设计选型及应用中该注意的问题进行了说明.最后,从长远角度探讨了该系统的发展前景.     

高层建筑节能采暖系统设计方案研究

高层建筑采暖系统由于各种原因常常产生水力失调的问题,结合建筑节能的发展趋势,提出优化采暖系统整体结构,通过智能系统主动控制相关阀门进行流量和压力调节的新型高层建筑采暖系统设计方案,以达到垂直方向和水平方向的水力平衡,降低整个系统的能源消耗和浪费,减少维护费用和管理费用并满足人们对室内环境的热舒适性要求的目的。     

基于动态热负荷的太阳能——地源热泵运行模式研究

建立了太阳能-地源热泵系统一体化模型,以大连地区气候条件为基础,计算了供暖季某天内房间热负荷的逐时值.在动态热负荷基础上,对联合供暖系统在不同串联运行模式和并联运行模式不同分流比的运行工况进行了模拟计算,将模拟结果与实脸数据对比,两者吻合较好.结果表明:房间热负荷的变化可影响热泵机组COP.联合运行模式在地温的恢复和系...     

Energy‐efficient design of greenhouse for Canadian Prairies using a heating simulation model

Greenhouses in northern climates require a large amount of supplemental heating for growing crops in winter seasons, so energy‐efficient design of greenhouses based on local climate is important to minimize the heating demand. In this study, greenhouse design parameters including shape, orientation, the angle of the roof, and width of the span have been studied for the conceptual design of conventional greenhouses for Canadian Prairies using a heating simulation model. Five different shapes of greenhouses including even‐span, uneven‐span, modified arch, vinery, and quonset shape have been selected for the study. The simulation results proved that the uneven‐span gable roof shape receives the highest solar radiation, whereas the quonset shape receives the lowest solar radiation. However, the quonset shape greenhouse requires about 7.6% less annual heating as compared to the gable roof greenhouse, but the quonset would not be adopted as multispan greenhouses. Therefore, the gable roof greenhouse is considered as energy efficient for the multispan gutter connected greenhouses whereas quonset shape as a free‐standing single‐span greenhouses. In high northern latitudes, the greenhouse with east‐west orientation is more energy efficient from heating and cooling point of view when the length‐width ratio of the greenhouse is more than 1. The heating energy saving potential of the large span width in single‐span greenhouses is relatively higher as compared to the multispan greenhouses.     

间接连接区域供热系统动态特性及控制策略仿真

基于质量和能量守恒定律及传热学原理创建间接连接区域供热系统动态模型。应用此模型,模拟分析不同循环质量流量时系统动态过程,并讨论存在管道热损失、补水、换热器及散热器富裕面积对系统动态特性的影响。结合2012年2月13日~2月19日逐时室外温度对整个系统进行动态模拟。结果表明:系统特征点温度响应与实测值误差较小,证明所建动态模型的准确性和实用价值。为补偿室外温度波动对供热系统的影响,采用四种PI控制策略模拟系统动态响应和分析比较其能耗。模拟分析显示:在室内温度控制方面,锅炉燃料质量流量与末端散热装置循环质量流量联合控制具有最佳控制精度;在系统能耗方面,锅炉燃料质量流量与一次网循环水量联合控制能耗最小,且管网温度波动最小,但个别时段室内温度波动略高。